Various industrial processes produce pollutant vapors and gases. These vapors and gases should be treated to avoid release of pollutants into the atmosphere. Other industries produce gases, which include end products, e.g., paint solvents. Recapture of end product increases the yield of a manufacturing process. Various processes have been developed to treat gas streams to serve these and other applications. Each seeks to remove contaminate gases from a standard atmospheric air (gas) stream.
Adsorption is a particularly useful technique. Adsorption removes a wide range of gas stream components. Adsorption process includes an adsorption step and a desorption step. During the adsorption step, the gas stream is brought into contact with sorbent in the form of granular activated carbon or zeolites. Gases adhere to the sorbent carbon or zeolite surfaces due to molecular attractive forces. The adsorbed gases are recovered during the desorption step. They are typically released by lowering pressure or by raising temperature. A typical method to raise temperature is by injection of steam. In conventional processes, recovered desorbed gases are often burned or converted to liquid through a refrigeration unit downstream of the desorption flow from an adsorption/desorption unit.
Photocatalytic decontamination systems (or other advanced oxidation decontamination processes) are typically cost effective in treating organic contaminants in wastewater in various applications. However, in applications in which there is a significant flow rate of wastewater to be decontaminated, or there are hydroxyl radical scavengers (e.g., alkalinity or chloride ions) in the contaminated media, the costs associated with such photocatalytic systems may become excessive or even prohibitive. While there may include multiple reasons for this increased expense, typically the principle cause of the prohibitive costs is the typical linear design of such systems and its high capital cost. What is needed are decontamination systems and methods that can decontaminate media at high-flow rates in a cost-effective manner.